The present invention is intended to perform an efficient countercurrent chromatography for separation of macromolecules and other materials by multi-layer coil planet centrifugation. The present invention is an improvement on the device of U.S. patent application Ser. No. 416,107 and it also relates to prior art such as shown in U.S. Pat. No. 4,228,009, entitled "Toroidal Coil Planet Centrifuge".
In U.S. patent application Ser. No. 416,107, the coil planet centrifuge holds a multi-layer coil which is subjected to a particular type of synchronous planetary motion, i.e., one rotation around its own axis during one revolution around the central axis of the apparatus in the same direction. As described earlier in said prior patent application, this planetary motion establishes a hydrodynamic equilibrium between two immiscible solvent phases in the coiled column which can be efficiently utilized for performing countercurrent chromatography. In this countercurrent chromatographic scheme, rotation of the coil contributes to stabilizing the stationary phase in the coil while the revolution of the coil produces mixing of the two phases to promote partition processing of solutes. In order to achieve the best results, these two effects should be optimized to yield a satisfactory retention level of the stationary phase and at the same time an efficient mixing of the two phases in the coil. Because of the nature of the synchronous planetary motion of the coil applied in this scheme, this optimization is most conveniently carried out by adjusting the ratio .beta. between the rotation radius r (distance between the center of rotation and a point on the holder) and the revolutional radius R (distance between the center of revolution and the center of rotation), or .beta.=r/R. The apparatus described in U.S. application Ser. No. 416,107 has a stationary shaft which extends along the central axis of the apparatus. Under this design of the apparatus, the rotational radius r becomes limited to be always smaller than the revolutional radius R, or to .beta. being smaller than 1. Two-phase solvent systems useful for separation of macromolecules often have particular physical properties such as an extremely lower interfacial tension, high viscosity, and small difference in density between the two phases. Such solvent systems exhibit a high tendency of emulsification in the coiled column and may not be applicable to countercurrent chromatography in the present scheme unless the .beta. of the system is made substantially greater than 1.